Preparation of mono epoxides and tertiary butyl alcohol using regenerated catalyst

ABSTRACT

In the preparation of tertiary butyl alcohol and a linear C 3  -C 12  mono epoxide by the epoxidation reaction of a linear C 3  -C 12  alpha mono olefin with tertiary butyl hydroperoxide in solution in tertiary butyl alcohol in the presence of a catalytic amount of a soluble complex of molybdenum with ethylene glycol, a portion of the catalyst that is used is a recycle (final) ethylene glycol solution of a complex of ethylene glycol with ammonium-containing molybdenum compounds prepared from ethylene glycol and a precipitate of solid ammonium-containing molybdenum compounds formed by saturating a heavy distillation fraction with ammonia to thereby form a liquid amination product containing a precipitate of solid ammonium-containing molybdenum compounds; the heavy distillation fraction being obtained by distillation of the epoxidation reaction product.

BACKGROUND OF THE INVENTION Technical Field of the Invention

This invention relates to an improvement in the method for preparing anepoxide of an alpha olefin such as propylene oxide and tertiary butylalcohol from a C₃ to C₁₂ alpha olefin such as propylene and tertiarybutyl hydroperoxide. More particularly, this invention relates to amethod for the preparation of propylene oxide and tertiary butyl alcoholfrom propylene and tertiary butyl hydroperoxide using a regeneratedcatalyst. Also, this invention relates to a process for preparing anepoxide of an alpha olefin such as propylene oxide and tertiary butylalcohol by the molybdenum catalyzed reaction of a C₃ to C₁₂ linear alphaolefin such as octene-1 or propylene With tertiary butyl hydroperoxidewherein a distillation fraction obtained from the epoxidation reactionmixture which contains residual molybdenum catalyst is reacted withammonia in liquid phase to provide a precipitate which is then reactedwith ethylene glycol to provide a regenerated molybdenum catalyst whichis used as a portion of the catalyst requirement to catalyze thereaction of the linear alpha olefin with tertiary butyl hydroperoxide.

PRIOR ART

Kollar U.S. Pat. Nos. 3,350,422 and 3,351,635 disclose and describe amethod for the preparation of olefin epoxides and alcohols by themolybdenum catalyzed reaction of an olefin with a tertiary alkylperoxide. It was recognized early on, as exemplified by Kollar U.S. Pat.Nos. 3,860,882, 3,947,500 and 3,947,501 that side reactions occur duringthe epoxidation of an olefin with a hydroperoxide in the presence of asoluble molybdenum catalyst that give rise to oxygen-containingby-products including acids, esters and ketones. In Kollar U.S. Pat.Nos. 3,860,662, 3,947,500 and 3,947,501, Kollar sought to improve theefficiency of the epoxidation reaction by reducing the acidiccharacteristics of the epoxidation reaction product by adding a basicmaterial to the reaction mixture, by adding a chemical reducing agent tothe reaction mixture or by hydrogenating the reaction mixture in thepresence of a hydrogenation catalyst.

In British Pat. No. 1,298,253, it was proposed to conduct the reactionon a continuous basis using an excess of tertiary butyl hydroperoxide ina first reaction zone and added propylene in a second reaction zone.

More recently, Marquis et al. in U.S. Pat. No. 4,891,437 have proposedto improve the efficiency of the process and to reduce by-productformation by the molybdenum catalyst catalyzed reaction of an olefinwith tertiary hydroperoxide or tertiary butyl hydroperoxide in areaction medium containing more than about 60 wt. % of polar components.Marquis et al. in U.S. Pat. No. 4,626,596 have also proposed the use ofa molybdenum/alkylene glycol complex prepared in a described manner inthe preparation of propylene oxide and tertiary butyl alcohol frompropylene and tertiary butyl hydroperoxide. Marquis et al. have alsoproposed the use of a molybdenum/sodium/ethylene glycol catalyst for thereaction in U.S. Pat. No. 4,845,251.

Catalyst Preparation

It was also recognized early on that the manner in which the molybdenumcatalyst was prepared would have an important bearing on the efficiencyof the reaction. Thus, in Kollar U.S. Pat. No. 3,362,972, proposed thepreparation of molybdenum catalysts by the reaction of a molybdenum saltwith a carboxylic acid.

Mattucci et al. in U.S. Pat. No. 3,668,227 disclose the preparation ofsoluble molybdenum compounds by reacting an organic molybdenum oxidewith a compound having vicinal hydroxyl groups (e.g., by the reaction ofmolybdenum acetyl acetonate with isobutylene glycol). The patenteesstated that in formation, or in use, the molybdenum compounds undergoprototrophic rearrangement to form molybdenum diol complexes having theformula given in the patent.

Bonetti in U.S. Pat. No. 3,480,563 propose the preparation of organicsoluble molybdenum catalysts by the reaction of molybdenum trioxide withan acyclic alcohol or a polyalkylene glycol monoether.

Molybdenum salt catalysts were prepared by Lines et al. in U.S. Pat. No.3,953,362 by the reaction of a molybdenum oxide with hydrogen peroxideand an amine in the optional presence of water or an alkylene glycol.

In Hagstrom et al. U.S. Pat. No. 3,991,090, propose the preparation ofmolybdenum derived compounds by the reaction of a molybdenum oxide withan organic compound containing vicinal hydroxyl groups in the presenceof a hydrohalide acid. Again, the preparation of molybdenum-alkyleneglycol complexes having the formula of the type disclosed by Mattucci etal. in U.S. Pat. No. 3,668,227 is stated to occur.

Subsequently, Marquis et al. sought to provide improved molybdenumcatalysts such as catalysts prepared in accordance with U.S. Pat. No.4,626,596 by the reaction of an ammonium-containing molybdenum compoundwith an alkylene glycol in the presence of a controlled amount of waterunder recited reaction conditions. Marquis et al. also disclose thepreparation of storage stable molybdenum/alkanol complexes by reactingan ammonium molybdate with an alkanol in the presence of controlledamounts of water under recited reaction conditions in U.S. Pat. No.4,650,886. Marquis et al. in U.S. Pat. No. 4,654,427 further describethe preparation of storage stable solutions of molybdenum/alkanolcomplexes by reacting a molybdenum oxide, ammonium hydroxide, and astraight chain or branched chain C₆ -C₁₃ alkanol. In Marquis et al. U.S.Pat. No. 4,703,027, disclose complexes prepared by reacting a solidammonium molybdate and a solid alkali metal molybdate with ethyleneglycol under controlled reaction conditions. Also, in Marquis et al.U.S. Pat. No. 4,758,681, a method of preparing a molybdenum catalyst isdisclosed wherein ethylene glycol is reacted with an ammoniumdimolybdate under recited reaction conditions. Also, in Marquis et al.U.S. Pat. No. 5,107,067, propose the preparation of a catalyst by thereaction of an ammonium-containing molybdenum compound with an alkyleneglycol in the presence of water followed by mild stripping of watersubsequent to the formation of the molybdenum/alkylene glycol complex.

Molybdenum Recovery

It is conventional practice to charge the epoxidation reaction mixtureto a distillation zone and there separate it into desired distillationfractions such as a recycle propylene fraction, a product propyleneoxide fraction, a tertiary butyl alcohol fraction and a heavydistillation fraction containing oxygenated by-products such as acids,esters and ketones and catalyst residue. The presence of the molybdenumcompounds in this heavy distillation fraction represents a probleminsofar as further workup or disposal of the fraction is concerned.

It was known from the workup of molybdenum-catalyzed coal liquefactionreaction products that molybdenum could be recovered by treating theprocess residue with an alkali to form water soluble molybdates whichcould then be roasted and leached to form a product which couldthereafter be extracted with water, acidified and ammoniated to form amolybdenum-bearing precipitate which could be dissolved in ammoniumhydroxide to form a solution to be used to catalyze coal liquefaction.See, for example, Sebenik et al. U.S. Pat. No. 4,374,100.

Insofar as the epoxidation of olefins is concerned, Khuri et al in U.S.Pat. No. 3,763,303 propose the process for the recovery of molybdenumfrom the epoxidation reaction product residue involving the steps ofwater extraction to obtain soluble molybdenum compounds, evaporation ofthe water to form a molybdenum-containing residue and calcination of themolybdenum-containing residue.

Lamke U.S. Pat. No. 3,887,361 propose to recover molybdenum by heatingthe reaction residue effluent at an elevated temperature in a closedreaction vessel in order to precipitate the molybdenum compounds.Poenisch in U.S. Pat. No. 4,485,074 propose to first add water to theorganic molybdenum-containing solution and to then heat the resultantaqueous mixture under pressure in order to precipitate the molybdenumcompounds.

Meyer et al. in U.S. Pat. No. 5,093,509 propose to recover molybdenum bya process that uses a synthetic high surface area amorphous magnesiumsilicate as a solid adsorbent. In Meyer et al. U.S. Pat. No. 5,101,052,propose to recover molybdenum by precipitating molybdenum from aresidual heavy distillation fraction with ammonia. Smith et al. in U.S.Pat. No. 5,128,492 describe molybdenum recovery by hydrogenation.British Pat. No. 1,317,480 also proposes to recover molybdenum compoundsby a process involving the use of water or aqueous ammonia to treat theheavy distillation fraction in order to form an aqueous phase containingmolybdenum from which the molybdenum can subsequently be recovered asmolybdenum trioxide.

Catalyst Regeneration

It has also been recognized that, where feasible, it would be desirableto regenerate at least a portion of the molybdenum contained in theepoxidation reaction product for reuse as catalyst for epoxidizing thereaction of an olefin with a hydroperoxide.

Thus, Sorgenti in U.S. Pat. No. 3,573,226 proposed a method forregenerating molybdenum contained in the heavy distillation fractionobtained by distillation of the epoxidation reaction product. Sorgentiproposes to utilize a bottoms fraction resulting from the distillationof the epoxidation reaction product which contains small amounts oftertiary butyl alcohol, unreacted tertiary butyl hydroperoxide, acidiccompounds, polyhydric compounds and used catalysts by adding metallicfinely divided molybdenum powder to the bottoms fraction followed byheating of the resultant mixture in order to solubilize the molybdenumand provide a fraction which could be recycled to the reactor to providefor the conversion of propylene and tertiary butyl hydroperoxide topropylene oxide and tertiary butyl alcohol with a conversion of about 81mol % of the hydroperoxide and a selectivity of 75% to propylene oxide,based on the hydroperoxide charged.

Levine et al. in U.S. Pat. No. 3,819,663 propose to take the heavydistillation fraction recovered from by distillation from theepoxidation reaction and subject it to further fractionation in a wipedfilm evaporator to obtain either a liquid molybdenum concentrate thatcan be mixed with tertiary butanol to provide a regenerated catalyst ora molybdenum powder that can be mixed with tertiary butyl alcohol,tertiary butyl hydroperoxide and monopropylene glycol to provide aregenerated catalyst. Three techniques for regenerating catalyst aredisclosed in Maurin U.S. Pat. No. 3,931,044. In accordance with oneembodiment, the residue fraction resulting from distillation of theepoxidation reaction mixture is calcined to form molybdenum trioxidewhich is then dissolved in aqueous ammonia to provide ammonia molybdatewhich can then be treated with a polyalcohol such as methyl-2,3-butanediol to provide a soluble molybdenum compound. In accordance with thesecond embodiment, the spent molybdenum-containing fraction is treatedwith an aqueous solution of ammonia without calcination to form anammonium molybdate which is then treated with a polyalcohol such asmethyl-2,3-butane diol to form a soluble molybdenum compound. Inaccordance with a third embodiment, the heavy distillation fraction isdirectly treated with gaseous ammonia to form a precipitate of ammoniummolybdate which is dissolved in a solvent such as acetone and thentreated with a polyalcohol such as methyl-2,3-butane diol. Aregeneration process wherein the molybdenum is thermally precipitatedfrom the heavy distillation fraction and then reacted with an alcoholand an organic dicarboxylic acid is disclosed in Isaacs U.S. Pat. No.4,598,057.

Marquis et al. in U.S. Pat. No. 5,093,506 disclose a process wherein adistillation fraction containing tertiary butyl hydroperoxide, tertiarybutyl alcohol, and carboxylic acid contaminants is partially neutralizedwith calcium oxide or calcium hydroxide to form a precipitate which isremoved and the resultant supernatant liquid is then recycled to theepoxidation reactor for use as an oxidant/solvent without causingprecipitation of molybdenum in the reaction zone.

SUMMARY OF THE INVENTION

The present invention is directed to a method for the preparation oftertiary butyl alcohol and propylene oxide by the reaction of an epoxideof a C₃ -C₁₂ linear alpha mono olefin such as a C₃ -C₁₂ linear alphamono olefin such as octene-1 or propylene with tertiary butylhydroperoxide in an epoxidation reaction zone in solution in tertiarybutyl alcohol in the presence of a soluble complex of molybdenum withethylene glycol to provide an epoxidation reaction product which isfractionated to provide a distillate olefin fraction, a distillateepoxide fraction, a distillate tertiary butyl alcohol fraction and aheavy liquid distillation fraction composed primarily of tertiary butylhydroperoxide, tertiary butyl alcohol, oxygen-containing impurities anddissolved molybdenum-ethylene glycol catalyst complex wherein the heavydistillation fraction is saturated with ammonia in a precipitation zoneto provide a solid ammonium-containing molybdenum precipitate which isrecovered and reacted in a catalyst regeneration zone with substantiallyanhydrous ethylene glycol to form an ethylene glycol solution of acomplex of ethylene glycol with ammonium-containing compounds present inthe precipitate and this solution, after removal of volatile by-productsis recycled for use as a catalyst for the conversion of additional monoolefin and additional tertiary butyl hydroperoxide to tertiary butylalcohol and mono olefin epoxide.

More particularly, the process of the present invention is a processwherein:

a. anhydrous ethylene glycol and anhydrous ammonium dimolybdate arecharged to a catalyst preparation reactor in an amount sufficient toprovide about 7 to about 20 moles of ethylene glycol per gram atom ofmolybdenum contained in the ammonium dimolybdate;

b. the resultant mixture is heated at a pressure of about 0 to about3,000 psig in a reaction temperature of about 70° to about 250° C. forabout 1 to 2 hours in order to form a solids-free solution of a complexof ethylene glycol with ammonium dimolybdate;

c. the solids-free solution of the complex of ethylene glycol with theammonium dimolybdate is held at a temperature of about 90° to about 110°C. for a time within the range of 0.5 to 5 hours sufficient to permitvaporization and removal of volatile by-products, including water, by anamount sufficient to provide an initial ethylene glycol solutioncontaining about 16 to about 52 wt. % of said complex of ethylene glycolwith said ammonium dimolybdate and having a molybdenum content of about6 to about 20 wt. % and a water concentration of about 0.5 to 6 wt. %;

d. a tertiary butyl alcohol solution of tertiary butyl hydroperoxide andpropylene charged to an epoxidation reaction zone together with acatalytic amount of a catalyst mixture composed of said initial ethyleneglycol solution of said complex with ethylene glycol with said ammoniumdimolybdate and a final ethylene glycol solution of a complex ofethylene glycol with ammonium-containing molybdenum compounds derivedfrom a precipitate of solid ammonium containing molybdenum compounds,the initial molar ratio of propylene to tertiary butyl alcohol solutionof active tertiary butyl hydroperoxide being about 1.05:1 to about 2:1and containing about 100 to about 600 ppm of catalyst mixture;

e. establishing epoxidation reaction conditions in the epoxidationreaction zone including a temperature of about 50° to about 180° C., anda residence time of about 1 to about 5 hours to thereby react thepropylene with the tertiary butyl hydroperoxide to provide anepoxidation reaction product comprising unreacted propylene, unreactedtertiary butyl hydroperoxide, propylene oxide, tertiary butyl alcohol,dissolved molybdenum ethylene glycol catalyst complex andoxygen-containing impurities;

f. resolving the epoxidation reaction products in a distillation zoneinto distillation fractions including a distillate propylene fraction, adistillate propylene oxide fraction, a distillate tertiary butyl alcoholfraction and a heavy liquid distillation fraction composed primarily oftertiary butyl hydroperoxide, tertiary butyl alcohol, oxygen-containingimpurities and dissolved molybdenum-ethylene glycol catalyst complex;

g. charging the heavy distillation fraction to a precipitation zone andsaturating it therein with ammonia to form a liquid amination productcontaining a precipitate of solid ammonium-containing molybdenumcompounds;

h. charging the amination product to a separation zone and thereinseparating the solid ammonium-containing molybdenum precipitate from theliquid medium;

i. recovering the solid ammonium-containing molybdenum precipitate;

j. charging the recovered solid ammonium-containing molybdenumprecipitate to a catalyst regeneration zone and mixing it therein withan amount of substantially anhydrous ethylene glycol sufficient toprovide about 7 to about 20 moles of ethylene glycol per gram atom ofmolybdenum contained in the solid ammonium-containing molybdenumprecipitate to form an ethylene glycol feed mixture;

k. heating the ethylene glycol feed mixture in a catalyst regenerationzone at a pressure of about 0 to about 3,000 psig and a reactiontemperature of about 70° to about 250° C. for a time within the range ofabout 1 to 2 hours sufficient to form a substantially solids-freeethylene glycol solution of a complex of ethylene glycol withammonium-containing compounds in said solid ammonium-containingmolybdenum precipitate;

1. holding said solids-free solution of said complex of ethylene glycolwith said ammonium-containing compounds in said catalyst regenerationzone at a temperature of about 90° to about 110° C. for a time, withinthe range of about 0.5 to about 5 hours, sufficient to permitvaporization and removal of volatile by-products, including water, by anamount sufficient to provide a final ethylene glycol solution containingabout 17 to about 52 wt. % of said complex of ethylene glycol with saidammonium-containing molybdenum compounds and having a molybdenum contentof about 6 to about 20 wt. % and a water concentration of about 0.5 toabout 6%; and

m. charging said thus-prepared final ethylene glycol solution to saidepoxidation reaction zone as said final ethylene glycol solution of acomplex of ethylene glycol with ammonium-containing molybdenum compoundsderived from a precipitate of solid ammonium-containing molybdenumcompounds.

Still more preferably, the process of the present invention is conductedin the above described manner on a continuous basis.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Starting Materials

The starting materials for the present invention are a C₃ -C₁₂ linearalpha mono olefin, tertiary butyl hydroperoxide, ethylene glycol, aninitial ethylene glycol solution of a complex of ethylene glycol withammonium dimolybdate and a final ethylene glycol solution of a complexof ethylene glycol with ammonium-containing molybdenum compounds derivedfrom a precipitate of solid ammonium-containing molybdenum compounds.

The linear alpha olefins to be used as feedstocks in accordance with thepresent invention are unbranched linear mono olefins containing from 3to 12 carbon atoms in the molecule including compounds such aspropylene, butene-1, pentene-1, hexene-1, octene-1, dodecene-1, etc. Apreferred mono olefin is propylene.

The tertiary butyl hydroperoxide that is used may be a standardindustrial grade of tertiary butyl hydroperoxide prepared, for example,by the oxidation of isobutane with oxygen to provide as a reactionproduct, a solution of tertiary butyl hydroperoxide and tertiary butylalcohol.

The ethylene glycol is preferably an industrial grade of ethylene glycolthat is substantially anhydrous. An industrial grade of ammoniumdimolybdate may also be used.

Preparation of the Initial Ethylene Glycol Solution

The starting materials for the preparation of the initial ethyleneglycol solution are ethylene glycol and ammonium dimolybdate. Thesubstantially anhydrous ethylene glycol and ammonium dimolybdate arecharged to a catalyst preparation zone in amounts sufficient to providea molar ratio of about 7 to about 20 moles of ethylene glycol per gramatom of molybdenum contained in the ammonium dimolybdate. The resultantfeed mixture is heated at a temperature of about 80° to about 130° C.and more preferably at a temperature of about 90° to about 100° C. at apressure of about 0 to about 3,000 psig, and preferably about 0 psig tothereby form a solution of a complex of ethylene glycol with theammonium dimolybdate in ethylene glycol. The resultant solution is heldat a temperature of about 90° to about 120° C. for about 0.5 to about 5hours sufficient to permit volatilization of volatile reactioncomponents including water and ammonia so as to provide an initialethylene glycol solution containing about 16 to about 52 wt. % of thecomplex of ethylene glycol with the ammonium dimolybdate and having amolybdenum content of about 6 to about 20 wt. % and a water concentrateof about 0.5 to about 6 wt. %.

Preparation of the Final Ethylene Glycol Complex

The final ethylene glycol complex is also prepared in the mannerdescribed above for the preparation of the initial ethylene glycolsolution. However, the source of the molybdenum is not the ammoniumdimolybdate specified above but, instead, is a precipitate of a solidammonium-containing molybdenum compound prepared and obtained in amanner to be described.

Epoxidation

In general, the alpha olefin is reacted with tertiary butylhydroperoxide in solution in tertiary butyl alcohol in the presence of acatalyst mixture composed of the initial ethylene glycol solution andthe final ethylene glycol solution by a process of the type disclosed inKollar U.S. Pat. No. 3,351,635, such as a process of the type disclosedin Marquis et al. U.S. Pat. Nos. 4,845,25I, 4,891,437 or 5,107,067.

In particular, the alpha olefin will be used in the form of an anhydrousolefin and the tertiary butyl hydroperoxide will be charged in the formof a solution of about 40 to about 75 wt. % of tertiary butylhydroperoxide in tertiary butyl alcohol. The reactants will be chargedin amounts such that the reaction mixture contains from about 200 toabout 600 ppm of the solubilized molybdenum catalyst and such that themolar ratio of alpha olefin to tertiary butyl hydroperoxide is withinthe range of about 1.05:1 to about 2:1 and, more preferably, within therange of from about 1.05:1 to about 1.8:1, and still more preferably inthe range of from about 1.05:1 to about 1.35:1. When the feed materialsto the epoxidation reaction zone are charged in the described fashion,the resultant reaction mixture will initially contain more than about 60wt. % of polar components (tertiary butyl alcohol and tertiary butylhydroperoxide). The olefin epoxide that is formed during the epoxidationreaction is also a polar material.

The epoxidation reaction may suitably be conducted at a temperaturewithin the range of about 50° to about 180° C., preferably within therange of about 90° to about 140° C., and more preferably within therange from about 100° to about 120° C.

The reaction is suitably conducted at a pressure sufficient to maintainthe reactants in liquid phase. Thus, for the higher alpha olefins suchas octene-1, the reaction can be conducted at atmospheric pressureHowever, a superatmospheric pressure is required for the more volatilelower alpha olefins, such as propylene and butene-1. In this situation,the lower pressure is suitably about 500 psig.

Higher pressures such as pressures within the range of about 500 toabout 3,000 psig. may be used if desired. Reaction time may suitablyvary from about 0.5 to about 5 hours, and more preferably from about 1.5to about 2 hours. The reaction may be conducted in a single reactionzone or in a plurality of reaction zones as described, for example, inMarquis et al. U.S. Pat. No. 4,891,437.

Molybdenum Recovery

In accordance with the present invention, the epoxidation reactionproduct formed in the above described fashion, is charged to adistillation zone and resolved therein into a plurality of fractionsincluding a distillate olefin fraction, a distillate olefin epoxidefraction, a distillate tertiary butyl alcohol fraction, a heavy liquiddistillation fraction containing tertiary butyl alcohol,oxygen-containing impurities and dissolved molybdenum-ethylene glycolcatalyst complex.

The heavy distillation fraction may then be treated, as for example, inthe manner disclosed in Meyer et al. U.S. Pat. No. 5,101,052.

In accordance with the present invention, a heavy distillation fractioncomprising tertiary butyl hydroperoxide, tertiary butyl alcohol andimpurities including about 0.4 to about 0.8 wt. % of dissolvedmolybdenum catalyst and lower aliphatic carboxylic acids resulting fromthe removal of olefin, olefin epoxide and tertiary butyl alcohol from anepoxidation reaction product is charged to a precipitation zone whichmay suitably comprise a reactor, such as an autoclave, provided withsuitable agitating means (e.g., an impeller), temperature control meanssuch as a jacket or coils through which a liquid heat exchange mediumcan be circulated, charge lines for the heavy distillation fraction andfor the ammonia and a discharge line for withdrawal of the treatedproduct. Within the precipitation zone the ammonia will react with themolybdenum compounds present in the heavy distillation fraction to forma reaction product comprising a molybdenum-containing precipitate thatcan be withdrawn from the precipitation zone. The precipitate can beremoved in any desired manner in a precipitate removal zone (e.g., byfiltration, centrifugation, etc.).

It has been discovered in accordance with the present invention thatwhen the heavy distillation fraction contains only about 0.8 wt. % orless of molybdenum (e.g., 0.4 to 0.8 wt. %), the precipitation of themolybdenum compounds will be essentially complete in that thatprecipitate will contain substantially all of the molybdenum charged tothe precipitation zone. It has been discovered that when heavydistillation fractions containing larger amounts of molybdenum are used,an undesirable higher percentage of the molybdenum will remain dissolvedin the treated heavy fraction.

The heavy distillation fraction will normally contain less than about 1wt. % of water and, therefore, ammonia should be used, as such, ratherthan in the form of an aqueous ammoniacal solution. The ammonia shouldpreferably be used in an amount which is equivalent to the amount ofmolybdenum in the heavy distillation fraction and, preferably, an excessof ammonia will be used, such as about 1 to about 200 moles of ammoniaper gram atom of molybdenum present in the heavy distillation fraction.Preferably, the heavy distillation fraction is saturated with ammonia.

The precipitation reaction can be conducted under ambient conditions oftemperature and pressure, although somewhat higher temperatures andpressures may be used, if desired, such as temperatures within the rangeof about 20° to 250° C. and pressures within the range of about 0 to3,000 psig. The contact time should be sufficient to insure that theprecipitation reaction goes to completion (e.g., 0.2 to 2 hours).

After the precipitation reaction is completed, the mixture ofprecipitate and treated heavy distillation fraction is withdrawn fromthe precipitation zone for removal of the precipitate. The precipitatecan be removed in any desired manner, e.g., filtration, centrifugation,evaporation, etc. Since the precipitate constitutes only a minor amountof the mixture of precipitate and treated heavy distillation fraction,filtration is preferred.

The filtrate obtained by the practice of the present invention willcontain only a residual amount of molybdenum (e.g., from 10 to 100 ppm).For example, it can be charged to a boiler as a fuel, or further treated(e.g., by vacuum distillation for the recovery of at least a portion ofthe tertiary butyl alcohol and/or tertiary butyl hydroperoxide containedtherein.

The precipitate will normally contain about 40 to about 58 wt. % ofmolybdenum.

Catalyst Regeneration

In accordance with the present invention, the solid ammonium-containingmolybdenum precipitate is charged to a catalyst regeneration zone whereit is mixed with substantially anhydrous ethylene glycol in an amountsufficient to provide about 7 to about 20 moles of ethylene glycol pergram atom of molybdenum contained in the solid ammonium-containingmolybdenum precipitate to thereby form an ethylene glycol feed mixture.A preferred ratio of ethylene glycol to gram atoms of molybdenum iswithin the range of about 8:1 to about 16:1. The water content of theethylene glycol feed mixture should preferably be within the range ofabout 0.1 to about 2 wt. %. The resultant mixture of ethylene glycolwith precipitate is heated in the catalyst regeneration zone at atemperature within the range of about 50° to about 150° C., and morepreferably within the range of about 90° to about 120° C. and a pressureof about 0 to about 3,000 psig., and preferably about 0 psig., for aperiod of time within the range of about 0.2 to 2 hours, and preferably0.5 to 1.5 hours.

In a preferred embodiment, the reactants are heated to about 90° toabout 120° C. for about 1 hour at ambient pressure, cooled and thensubjected to a vacuum of 10 to 100 mm Hg for 30 to 60 minutes to removewater, ammonia and excess ethylene glycol. Sufficient volatile materialsshould be removed overhead so as to provide a liquid product containingfrom about 80 to about 95 wt. % of the initial charge and should have awater content of about 0.1 to about 2 wt. % and contain from about 6 wt.% to about 20 wt. % of molybdenum.

The resultant thus formed final ethylene glycol solution of a complex ofethylene glycol with ammonium-containing molybdenum compounds can thenbe recycled to the epoxidation reaction zone as the final ethyleneglycol solution of a complex of ethylene glycol with ammonium-containingmolybdenum compounds derived from a precipitate of solidammonium-containing molybdenum compounds. Preferably, the catalystmixture will contain from about 40 to about 60 wt. % of the initialethylene glycol solution and, correspondingly, from about 60 to about 40wt. % of the final ethylene glycol solution.

BRIEF DESCRIPTION OF THE DRAWING

In the drawing, the Figure is a schematic drawing of a preferredreaction and purification sequence that may be used in the practice ofthe present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Turning now to the drawing, there is shown a schematic flow sheetillustrating the preferred method of practicing the process of thepresent invention.

In accordance with the present invention, a catalyst preparation zone100 is provided to which substantially anhydrous ethylene glycol ischarged by a line 102 and to which ammonium dimolybdate is charged byway of a line 104. The ethylene glycol and ammonium dimolybdate arecharged in a manner such that the resultant mixture of ethylene glycolwith ammonium dimolybdate will contain from about 7 to about 20 moles ofethylene glycol per gram atom of molybdenum in the ammonium dimolybdateand, more preferably, from about 8 to about 16 moles of ethylene glycolper gram atom of molybdenum contained in the ammonium dimolybdate.

The resultant mixture will normally contain water within the range ofabout 0.1 to about 2 wt. %.

In accordance with the present invention, the resultant mixture ofethylene glycol with ammonium dimolybdate is heated in the catalystpreparation zone which may suitably comprise an autoclave. The mixtureis heated at a temperature between about 50° and about 150° C., and morepreferably from 90° to 120° C., preferably at atmospheric pressure for aperiod of time within the range of about 0.2 to about 2 hours, and morepreferably 0.5 to about 1.5 hours in order to react the ammoniumdimolybdate with some of the ethylene glycol present in the reactionmixture to form an ethylene glycol solution of an ethyleneglycol-ammonium dimolybdate complex. Thereafter, the reaction mixture iscooled and then subjected to a vacuum of 10 to about 100 mm Hg for 30 to60 minutes while raising the temperature of the reaction medium to about90° to 110° C. to provide a liquid bottoms product comprising about 80to about 95 wt. % of the total initial charge weight and having a watercontent of about 0.1 to about 2 wt. %. This resultant solution of anethylene glycol/ammonium dimolybdate complex in ethylene glycol willnormally contain 6 to about 20 wt. % of molybdenum.

The catalyst preparation zone may suitably be operated as a batchoperation and the desired initial ethylene glycol solution may bedischarged from the catalyst preparation zone by a line 106 leading to astorage tank 108 from which the ethylene glycol solution may be chargedto a reaction zone 10 by a molybdenum catalyst charge line 14.

Suitably, the tertiary butyl hydroperoxide that is charged to theepoxidation reaction zone 10 by way of line 16 is about a 40 to about 75wt. % solution of tertiary butyl hydroperoxide in tertiary butylalcohol. The catalyst is charged to the epoxidation reaction zone 10 bythe charge line 14 in an amount such as to provide from about 50 toabout 1000 ppm of molybdenum, based on the total of the reactantscharged and, more preferably, from about 200 to 600 ppm. The epoxidationreaction is preferably conducted at superatmospheric pressure such as apressure of about 300 to 1000 psig.

Propylene is charged by way of a line 12 to the epoxidation reactionzone 10 in an amount sufficient to provide an initial charge ratio ofpropylene to tertiary butyl hydroperoxide within the range of about1.05:1 to about 2:1, and more preferably in the range of about 1.05:1 toabout 1.8:1, and still more preferably in the range of about 1.05:1 toabout 1.35:1.

When the reaction is conducted on a continuous basis, as illustrated inthe drawing, the feed materials are charged to the epoxidation reactionzone 10 through the lines 12, 14 and 16 at rates sufficient to maintainthe desired concentration of reactants and an equivalent volume ofepoxidation reaction mixture is withdrawn from the epoxidation reactionzone 10 by way of a discharge line 18. The reaction product dischargedby the line 18 will normally comprise a minor amount of unreactedpropylene, tertiary butyl hydroperoxide, propylene oxide, tertiary butylalcohol, including tertiary butyl alcohol formed by the reaction of thetertiary butyl hydroperoxide with propylene, the molybdenum catalyst andimpurities such as propane, propionaldehyde, acetone, methanol,isopropanol, water, acetaldehyde, methyl formate, acetic acid, formicacid, isobutyric acid, esters, and hydrocarbons containing 6 or morecarbon atoms and high boiling residue components.

The reaction product 18 is charged to an epoxidation reaction productdistillation zone 20 where it is separated by distillation into desiredfractions in accordance with methods known to those skilled in the art.For example, the distillation sequence disclosed in British Pat. No.1,298,253 may be used.

One of the distillate products that is recovered in the zone 20 is apropylene fraction which is discharged by a line 22 controlled by avalve 24 and provided with a branch line 26 controlled by a valve 28 inorder to permit the recycle of unreacted propylene to the epoxidationreaction zone 10 through the propylene charge line 12.

Another distillate fraction that is obtained is a propylene oxideproduct fraction 30 which is discharged by the line 30.

The propylene oxide fraction may be purified in a propylene oxidepurification zone (not shown) by known techniques such as, for example,those disclosed in Burnes et al. U.S. Pat. No. 3,715,284, Schmidt et al.U.S. Pat. Nos. 3,909,366, and 3,881,996, Jubin U.S. Pat. No. 3,607,669,Schmidt U.S. Pat. No. 3,843,488 or 4,140,588.

Another product that is recovered from the epoxidation reaction productdistillation zone 20 is a tertiary butyl alcohol distillate product 40which may be further purified, if desired, to remove oxygenatedimpurities therefrom by catalytic treatment as disclosed, for example,in Sanderson et al. U.S. Pat. No. 4,704,482, 4,705,903 or 4,742,149.

A heavy distillation fraction 50, usually a bottoms fraction, is alsodischarged from the epoxidation reaction product distillation zone 20.As described by Levine U.S. Pat. No. 3,819,663 and Sweed U.S. Pat. No.4,455,283, the heavy distillation fraction will contain substantiallyall of the molybdenum catalyst initially charged to the epoxidationreaction zone 10 by way of the line 14. The heavy distillation fraction50 will contain other products such as tertiary butyl hydroperoxide,tertiary butyl alcohol and impurities including oxygenates lighter thantertiary butyl alcohol such as acetaldehyde, acetone, isopropyl alcohol,etc., oxygenates heavier than tertiary butyl alcohol but lighter thantertiary butyl hydroperoxide, and residue components heavier thantertiary butyl hydroperoxide such as propylene glycol tertiary butylethers, etc. As indicated, the heavy distillation fraction 50 will alsocontain carboxylic acids such as formic acid, acetic acid and isobutyricacid and esters.

Although the molybdenum catalyst is present in the epoxidation reactionzone 10 in an amount in the range of about 50 to 1,000 ppm, and usually200 to 600 ppm, it is progressively concentrated in the epoxidationreaction product distillation zone 20 and is normally present in theheavy distillation fraction 50 in an amount in the range of about 0.4 to0.8 wt. % (about 4,000 to 8,000 ppm).

The molybdenum-contaminated heavy distillation fraction 50, inaccordance with the present invention, is charged to a precipitationzone 60 which may comprise a reaction vessel such as an autoclave whichis equipped with suitably agitation means (e.g., an impeller) andsuitably temperature control means such as an external jacket orinternal coils through which a heat exchange medium can be circulated.Within the precipitation zone the heavy distillation fraction 50 isbrought into contact with ammonia which is charged by an ammonia chargeline 52 in at least an equimolar amount, based on the molybdenum contentof the heavy distillation fraction 50 and, preferably, in a molarexcess. The ammonia is preferably used in the form of anhydrous ammoniain order to minimize the water content of the treated heavy distillationfraction 50. The ammonia is suitably brought into contact with the heavydistillation fraction 50 under ambient temperature and pressureconditions, although higher temperatures and/or pressures may be used,such as temperatures within the range of about 20° to 250° C. andpressures within the range of 0 to about 3,000 psig. The contact timeshould be sufficient to ensure as complete a reaction of the ammoniawith the molybdenum as is reasonably possible and to ensuresubstantially complete precipitation of the product, such as a contacttime of about 0.2 to 2 hours.

The thus-formed slurry of precipitate in the treated heavy distillationfraction 50 is discharged from the precipitation zone 60 by a slurrydischarge line 62 leading to a precipitate separating zone, such as afiltration zone 70 where the slurry is resolved into a precipitate thatis removed by a discharge line 72 and a substantially molybdenum-freefiltrate fraction that is discharged by a filtrate discharge line 74controlled by a valve 76.

The precipitate 72 is then charged to catalyst preparation zone 100together with ethylene glycol, preferably anhydrous, charged by a line102. The resultant final catalyst solution is discharged from thecatalyst regeneration zone 80 by a line 106 leading to the junction 112where it is mixed with the initial ethylene glycol solution to providethe catalyst reaction mixture discharge from the junction 112 by theline 14 leading to the epoxidation reaction zone 10.

WORKING EXAMPLES

The following working examples are given by way of illustration and notas limitations in the scope of the invention as claimed herein.

Preparation of Final Catalyst Solution

A series of catalyst compositions (final ethylene glycol solution) wereprepared by reacting ethylene glycol with the molybdenum precipitateproduced by ammonia treatment of the heavy distillation fraction fromepoxidation.

EXAMPLE 1 (No. 6695-1)

About 4.8 g of an ammonium molybdate-containing precipitate containingabout 48.4% molybdenum were charged to a 250 ml flask together with 15.0g of substantially anhydrous ethylene glycol. The flask was equippedwith a magnetic stirrer, a K-head, a condenser and a nitrogen purge. Theflask was heated to 100° C. and held at this temperature for about 1hour. Thereafter the contents of the flask were cooled and thensubjected to a vacuum to take overhead about 1.3 g of material, leavinga total of 16.5 g of material in the bottom of the flask.

Since the total charge to the flask was 19.8 g, the bottoms resultingafter vacuum evacuation amounted to about 83% of the charge. On analysisit was found that a total of 2.323 g of molybdenum were charged and thatthe molybdenum in the bottoms resulting from vacuum distillationamounted to 2.31 g indicating that 99.4 wt. % of the charged molybdenumwas incorporated into the catalyst. The final bottoms was found byanalysis to contain 3.17 wt. % of water and the analysis was 14.0 wt. %molybdenum, acid number 160.78, nitrogen (micro Kjeldahl) 0.84.

EXAMPLE 2 (No. 6695-2)

About 6.2 g of an ammonia precipitate containing about 48.0% molybdenumwere charged to a 250 ml flask together with 19.2 g of substantiallyanhydrous ethylene glycol. The flask was equipped with a magneticstirrer, a K-head, a condenser and a nitrogen purge. The flask washeated to 100° C. and held at this temperature for about 1 hour.Thereafter the contents of the flask were cooled and then subjected to avacuum to take overhead about 1.7 g of material, leaving a total of 21.2g of material in the bottom of the flask.

Since the total charge to the flask was 25.4 g, the bottoms resultingafter vacuum evacuation amounted to about 83.1% of the charge. Onanalysis it was found that a total of 2.976 g of molybdenum were chargedand that the molybdenum in the bottoms resulting from vacuumdistillation amounted to 3.307, indicating an analytical error, becausethis would indicate that 111% of the charged molybdenum was incorporatedinto the catalyst. The final bottoms was found by analysis to contain1.84 wt. % of water and the analysis was 15.6 wt. % molybdenum, acidnumber 169.36, nitrogen (micro Kjeldahl) 0.72. The analytical error islikely in the Atomic Absorption determination of molybdenum in thecatalyst bottoms. The maximum amount of molybdenum that could be in thebottoms (basis the 2.976 g charged) would be 14.0% molybdenum.

EXAMPLE 3 (No. 6695-3)

About 5.0 g of an ammonia precipitate containing about 46.0% molybdenumwere charged to a 250 ml flask together with 14.72 g of substantiallyanhydrous ethylene glycol. The flask was equipped with a magneticstirrer, a K-head, a condenser and a nitrogen purge. The flask washeated to 100° C. and held at this temperature for about 1 hour.Thereafter the contents of the flask were cooled and then subjected to avacuum to take overhead about 2.4 g of material, leaving a total of 15.1g of material in the bottom of the flask.

Since the total charge to the flask was 19.72 g, the bottoms resultingafter vacuum evacuation amounted to about 76.6 wt. % of the charge. Onanalysis it was found that a total of 2.300 g of molybdenum were chargedand that the molybdenum in the bottoms resulting from vacuumdistillation amounted to 2.356, indicating a small analytical error,because this would indicate that 102.4 wt. % of the charged molybdenumwas incorporated into the catalyst. The final bottoms was found byanalysis to contain 1.53 wt. % of water and the analysis was 15.6 wt. %molybdenum, acid number 180.54. The maximum amount of molybdenum thatcould be in the bottoms (basis 2.300 g molybdenum charged) would be15.23%.

EXAMPLE 4 (No. 6695-4)

About 4.4 g of an ammonia precipitate containing about 5.0% molybdenumwere charged to a 250 ml flask together with 14.0 g of substantiallyanhydrous ethylene glycol. The flask was equipped with a magneticstirrer, a K-head, a condenser and a nitrogen purge. The flask washeated to 100° C. and held at this temperature for about 1 hour.Thereafter the contents of the flask were cooled and then subjected to avacuum to take overhead about 1.7 g of material, leaving a total of 14.8g of material in the bottom of the flask.

Since the total charge to the flask was 18.8 g, the bottoms resultingafter vacuum evacuation amounted to about 78.7 wt. % of the charge. Onanalysis it was found that a total of 2.200 g of molybdenum were chargedand that the molybdenum in the bottoms resulting from vacuumdistillation amounted to 2.2644 g, indicating a small analytical error,because this would indicate that about 103% of the charged molybdenumwas incorporated into the catalyst. The final bottoms was found byanalysis to contain 0.04 wt. % of water and the analysis was 15.3 wt. %molybdenum, acid number 162.14, nitrogen (micro Kjeldahl) 0.655. Thepercent molybdenum in the bottoms (basis 2.20 g molybdenum charged)could be a maximum of 14.86%.

EXAMPLE 5 (No. 6695-5)

About 6.0 g of an ammonia precipitate containing about 47.0% molybdenumwere charged to a 250 ml flask together with 18.33 g of substantiallyanhydrous ethylene glycol. The flask was equipped with a magneticstirrer, a K-head, a condenser and a nitrogen purge. The flask washeated to 100° C. and held at this temperature for about 1 hour.Thereafter the contents of the flask were cooled and then subjected to avacuum to take overhead about 2.9 of material, leaving a total of 18.9 gof material in the bottom of the flask.

Since the total charge to the flask was 24.33 g, the bottoms resultingafter vacuum evacuation amounted to about 77.7% of the charge. Onanalysis it was found that a total of 2.820 g of molybdenum were chargedand that the molybdenum in the bottoms resulting from vacuumdistillation amounted to 2.927, indicating a small analytical error,because this would indicate that 105% of the charged molybdenum wasincorporated into the catalyst. The final bottoms was found by analysisto contain 0.11 wt. % of water and the analysis was 15.7 wt. %molybdenum, acid number 173.13, nitrogen (micro Kjeldahl) 1.02. Themaximum percent molybdenum that could be in the bottoms would be 14.92%(basis the 2.82 g molybdenum charged).

The results of the foregoing catalyst preparation experiments aresummarized in Table I.

                                      TABLE I                                     __________________________________________________________________________    Molybdenum Catalyst Preparation from Molybdenum Solids                        Produced by Ammonia Treatment of Epoxidation Catalyst Bottoms                 __________________________________________________________________________                           Grams           Stripping                                                Grams                                                                              Moly                                                                              Mole Rxn Rxn                                                                              Temp                                                                              Time                                         Grams                                                                             Moles                                                                             Solid                                                                              (Gr A                                                                             Ratio                                                                              Temp                                                                              Time                                                                             °C.                                                                        min.                               NB Run #                                                                            ROH of EG                                                                             of EG                                                                             (% MO)                                                                             Moly)                                                                             EG/MO                                                                              °C.                                                                        Hrs                                                                              (pressure)                             __________________________________________________________________________    6695-1-2                                                                            EG  15.00                                                                             0.242                                                                             4.80 2.323                                                                             10.00                                                                              100 1.0                                                                              50-95                                                                             20                                                   (48.4)                                                                             (.024)          (8-9 mm Hg)                            6695-2-2                                                                            EG  19.20                                                                             0.309                                                                             6.20 2.976                                                                              9.97                                                                              100 1.0                                                                              50-95                                                                             45                                                   (48.0)                                                                             (.031)          (9 mm Hg)                              6695-3-2                                                                            EG  14.70                                                                             0.237                                                                             5.00 2.300                                                                              9.88                                                                              100 1.0                                                                              35-98                                                                             20                                                   (46.0)                                                                             (.024)                                                                                        (9 mm Hg)                              6695-4-2                                                                            EG  14.00                                                                             0.226                                                                             4.40 2.200                                                                              9.87                                                                              100 1.0                                                                              38-94                                                                             30                                                   (50.0)                                                                             (.023)          (8 mm Hg)                              6695-5-2                                                                            EG  18.30                                                                             0.295                                                                             6.00 2.820                                                                             10.03                                                                              100 1.0                                                                              55-95                                                                             25                                                   (47.0)                                                                             (.029)          (8 mm Hg)                              __________________________________________________________________________                                     Comments & Observations                      NB Run #                                                                            % Moly in Cat                                                                         % N2                                                                              % H2O                                                                              Acid #                                                                            % MOIN                                                                              (Theoretical % Moly)                         __________________________________________________________________________    6695-1-2                                                                            14.0    0.84                                                                              3.17 160.78                                                                             99.4 Starting solids from RAM                                                      were 6655-38-12 from liq                                                      NH3 treatment of epoxidn                                                      cat btms (0.56 wt % moly)                                                     Catalyst was clear, brown                    6695-2-2                                                                            15.6    0.72                                                                              1.84 169.36                                                                            110.6 Starting solids from RAM                                                      were 6547-61-8 from liq                                                       NH3 treatment of epoxidn                                                      cat btms (0.56 wt % moly)                                                     Catalyst was clear, brown                    6695-3-2                                                                            15.6    --  1.53 180.54                                                                            102.4 Starting solids from RAM                                                      were 6547-63-6 from gas-                                                      eous NH3 treatment of                                                         epoxidn cat btms (0.56                                                        wt % moly) Catalyst was                                                       clear, brown                                 6695-4-2                                                                            15.3    0.66                                                                              0.04 162.14                                                                            102.9 Starting solids from RAM                                                      were 6547-64-7 from gas-                                                      eous NH3 treatment of                                                         epoxidn cat btms (0.56                                                        wt % moly) Catalyst was                                                       clear, brown                                 6695-5-2                                                                            15.7    1.02                                                                              0.11 173.13                                                                            105.2 Starting solids from RAM                                                      were 6547-69-5 from liq                                                       NH3 treatment of epoxidn                                                      cat btms (0.56 wt % moly)                                                     Catalyst was clear, brown                    __________________________________________________________________________

EPOXIDATION EXAMPLES

In the following examples, the catalyst complexes of Examples 1-5 wereused to catalyze the reaction of octene-1 with tertiary butylhydroperoxide. Octene-1 was used rather than propylene for conveniencein the laboratory and in order to more conveniently obtain an evaluationof the effectiveness of the catalyst of Examples 1-5. The epoxidationreaction can be run at atmospheric pressure in laboratory glassware whenthe olefin is octene-1.

The epoxidation results are summarized in attached Table II.

                                      TABLE II                                    __________________________________________________________________________    Epoxidation of Octene-1 with Moly/EG Catalysts Made from                      Moly Solids from Ammonia Treatment of Epoxidation Cat Bottoms                                      wt %                                                                          TBHP                  Selectivity                              Oct/           in the                                                                             Octene                                                                             Octene                                                                             wt % TBHP                                                                            to Octene                                TBHP                                                                              Rxn Rxn                                                                              Cata-                                                                             TBHP/                                                                              Area Oxide                                                                              Remain-                                                                              Oxide Basis                                                                             Yield                                                                              Conver-                   Mole                                                                              Temp                                                                              Time                                                                             lyst                                                                              TBA  %    Area %                                                                             ing by TBHP  TBHP                                                                              Octene                                                                             sion of             NB Run #                                                                            Ratio                                                                             °C.                                                                        Hrs.                                                                             ppm Solution                                                                           (GLC)                                                                              (GLC)                                                                              Titration                                                                            Conv  Conv                                                                              Oxide                                                                              Octene              __________________________________________________________________________    6695-7 A                                                                            2.50/1                                                                            95.0                                                                              1.0                                                                              .03500                                                                            73.25 H                                                                            52.486                                                                             20.085                                                                             3.02   73.32 86.44                                                                             63.36                                                                              24.18               6695-8 B                                                                            "   "   "  "   "    53.413                                                                             19.484                                                                             3.11   71.41 86.06                                                                             61.45                                                                              22.94               6695-9 C                                                                            "   "   "  "   "    52.715                                                                             21.796                                                                             2.64   77.76 88.19                                                                             68.58                                                                              24.12               6695-10 D                                                                           "   "   "  "   "    51.749                                                                             22.271                                                                             2.47   78.88 88.94                                                                             70.16                                                                              25.43               6695-11 E                                                                           "   "   "  "   "    53.000                                                                             20.226                                                                             3.55   75.65 84.12                                                                             63.64                                                                              23.72               6695-12 F                                                                           "   "   "  "   "    51.908                                                                             21.263                                                                             2.92   77.07 86.91                                                                             66.98                                                                              25.20               6695-13 F                                                                           "   "   "  "   "    52.733                                                                             21.289                                                                             3.32   78.66 85.15                                                                             66.98                                                                              24.10               6695-14 F                                                                           "   "   "  "   "    52.022                                                                             21.708                                                                             2.92   78.66 86.92                                                                             68.38                                                                              25.04               6695-15 C                                                                           "   "   "  .05250                                                                            "    51.361                                                                             22.789                                                                             2.52   81.35 88.70                                                                             72.16                                                                              25.91               6695-16 D                                                                           "   "   "  "   "    50.378                                                                             24.273                                                                             1.98   83.38 91.19                                                                             75.99                                                                              27.85               6695-19 F                                                                           "   "   "  "   "    51.836                                                                             22.509                                                                             3.16   82.71 85.83                                                                             70.99                                                                              25.20               6695-34 A                                                                           "   "   "  .03500                                                                            58.03 I                                                                            47.577                                                                             21.481                                                                             1.12   77.06 94.60                                                                             72.90                                                                              26.25               6695-35 B                                                                           "   "   "  "   "    46.691                                                                             22.523                                                                             1.57   82.85 92.40                                                                             76.55                                                                              27.45               6695-36 C                                                                           "   "   "  "   "    46.820                                                                             20.278                                                                             1.55   74.46 92.50                                                                             68.85                                                                              27.31               6695-37 D                                                                           "   "   "  "   "    56.675                                                                             21.895                                                                             1.46   80.20 92.95                                                                             74.55                                                                              27.36               6695-38 E                                                                           "   "   "  "   "    47.504                                                                             21.110                                                                             1.60   77.81 92.25                                                                             71.80                                                                              26.17               6695-39 F                                                                           "   "   "  "   "    47.189                                                                             22.429                                                                             1.47   81.99 92.90                                                                             76.15                                                                              26.76               6695-40 F                                                                           "   "   "  "   "    47.318                                                                             21.923                                                                             2.29   83.88 88.93                                                                             74.60                                                                              26.42               6695-41 F                                                                           "   "   "  "   "    47.215                                                                             21.959                                                                             1.97   82.62 90.45                                                                             74.75                                                                              26.56               6695-42 G                                                                           "   "   "  "   "    47.497                                                                             21.151                                                                             2.16   80.28 89.55                                                                             71.90                                                                              26.20               6695-43 G                                                                           "   "   "  "   "    46.857                                                                             22.799                                                                             1.94   85.46 90.65                                                                             77.45                                                                              27.22               6695-44 G                                                                           "   "   "  "   "    47.508                                                                             21.459                                                                             2.02   80.86 90.25                                                                             73.00                                                                              26.15               __________________________________________________________________________     A = Catalyst was a moly/EG catalyst made from recovered moly solids           (catalyst #66951-2).                                                          B = Catalyst was a moly/EG catalyst made from recovered moly solids           (catalyst #66952-2).                                                          C = Catalyst was a moly/EG catalyst made from recovered moly solids           (catalyst #66953-2).                                                           D = Catalyst was a moly/EG catalyst made from recovered moly solids          (catalyst #66954-2).                                                          E = Catalyst was a moly/EG catalyst made from recovered moly solids           (catalyst #66955-2).                                                          F = Catalyst was a standard moly/EG catalyst (603281-2) containing 12.5       wt. % moly.                                                                   G = Catalyst was a standard moly/EG catalyst (648833-17) made by the pilo     plant and used in their unit.                                                 H = TBHP had a water content of 0.41 wt. %.                                   I = TBHP had a water content of 0.09 wt. %.                                   In the top section results are within experimental error in terms of          selectivity, conversion and yield.                                            In the bottom section, average selectivities for the 5 recovered catalyst     are within experimental error.                                           

A statistical analysis was made of the results reported in Table II.From the statistical analysis it was concluded that:

A) The difference in means for selectivity to octene oxide isstatistically significant at the 95-98% probability level for virgin andrecycled catalyst. The selectivity is higher with virgin catalyst.

B) The difference in means is not statistically significant for TBHPconversion, octene oxide yield and octene conversion at the 95-98%probability level.

Having thus described our invention, what is claimed is:
 1. In a methodfor the preparation of tertiary butyl alcohol and a C₃ -C₁₂ linear alphaolefin mono epoxide wherein a C₃ -C₁₂ linear alpha mono olefin andtertiary butyl hydroperoxide are reacted in an epoxidation reaction zonein solution in tertiary butyl alcohol in the presence of a catalyticamount of a soluble complex of molybdenum with ethylene glycol toprovide an epoxidation reaction product comprising unreacted alphaolefin, unreacted tertiary butyl hydroperoxide, olefin epoxide, tertiarybutyl alcohol, dissolved molybdenum-ethylene glycol catalyst complex,and oxygen-containing impurities, and wherein the said epoxidationreaction product is resolved into distillation fractions in adistillation zone, including a distillate alpha olefin fraction, adistillate alpha olefin mono epoxide fraction, a distillate tertiarybutyl alcohol fraction and a heavy liquid distillation fraction composedprimarily of tertiary butyl hydroperoxide, tertiary butyl alcohol,oxygen-containing impurities and dissolved molybdenum-ethylene glycolcatalyst complex, the improvement which comprises the steps of:a.charging said heavy distillation fraction to a precipitation zone andsaturating said heavy distillation fraction in said precipitation zonewith ammonia to thereby form a liquid amination product containing aprecipitate of solid ammonium-containing molybdenum compounds, b.charging said amination produce to a separation zone and thereinseparating the solid ammonium-containing molybdenum precipitatetherefrom, c. recovering said solid ammonium-containing molybdenumprecipitate, d. charging said recovered solid ammonium-containingmolybdenum precipitate to a catalyst regeneration zone and mixing ittherein with an amount of substantially anhydrous ethylene glycolsufficient to provide about 7 to about 20 moles of ethylene glycol pergram atom of molybdenum contained in said solid ammonium-containingmolybdenum precipitate to form an ethylene glycol feed mixture, e.heating said ethylene glycol feed mixture in said catalyst regenerationzone at a pressure of about 0 to 3,000 psig and a reaction temperatureof about 70° to about 250° C. for a time within the range of about 1 to2 hours sufficient to form a substantially solids-free ethylene glycolsolution of a complex of ethylene glycol with the ammonium-containingcompounds in said solid ammonium-containing molybdenum precipitate, f.holding said solids-free solution of said complex of ethylene glycolwith the said ammonium-containing compounds in said catalystregeneration zone at a temperature of about 90° to about 110° C. for atime, within the range of about 0.5 to 5 hours, sufficient to permitvaporization and removal of volatile by-products, including water, by anamount sufficient to provide an ethylene glycol solution containingabout 17 to about 52 wt. % of said complex of ethylene glycol with saidammonium-containing molybdenum compounds and having a molybdenum contentof about 6 to about 20 wt. % and a water concentration of about 0.5 to 6wt. %, and g. charging said thus-prepared ethylene glycol solution ofsaid complex of ethylene glycol with said ammonium-containing molybdenumcompounds to said epoxidation reaction zone to catalyze the reaction ofadditional alpha olefin with additional tertiary butyl hydroperoxide insolution in tertiary butyl alcohol to provide an additional epoxidationreaction product.
 2. A method as in claim I wherein the alpha olefin ispropylene and wherein the heavy liquid distillation fraction issaturated with ammonia in the said precipitation zone underprecipitation conditions including a temperature of about 20° to about250° C. and a pressure of about 0 to about 3,000 psig.
 3. A method as inclaim 2 wherein the heavy liquid distillation fraction contains fromabout 0.4 to about 0.8 wt. % of molybdenum, the said filtrate containsabout 50 to about 200 ppm of molybdenum and the said precipitatedammonium-containing molybdenum compounds contain about 40 to about 50wt. % of molybdenum.
 4. A method for the molybdenum-catalyzedpreparation of tertiary butyl alcohol and propylene oxide from propyleneand tertiary butyl hydroperoxide which comprises the steps of:a.charging substantially anhydrous ethylene glycol and anhydrous ammoniumdimolybdate to a catalyst preparation reactor and mixing them therein inamounts sufficient to provide about 7 to about 20 moles of ethyleneglycol per gram atom of molybdenum contained in said ammoniumdimolybdate, b. heating said mixture of ethylene glycol and saidammonium dimolybdate in said catalyst preparation reactor at a pressureof about 0 to 3,000 psig and a reaction temperature of about 70° toabout 250° C. for an amount of time, within the range of about 1 to 2hours sufficient to form a solids-free solution of a complex of ethyleneglycol with said ammonium dimolybdate, c. holding said solids-freesolution of said complex of ethylene glycol with the said ammoniumdimolybdate in said catalyst preparation reactor at a temperature ofabout 90° to about 110° C. for a time, within the range of about 0.5 to5 hours, sufficient to permit vaporization and removal of volatileby-products, including water, by an amount sufficient to provide aninitial ethylene glycol solution containing about 80 to about 95 wt. %of said complex of ethylene glycol with said ammonium dimolybdate andhaving a molybdenum content of about 6 to about 20 wt. % and a waterconcentration of about 0.5 to 6 wt. %, d. charging a tertiary butylalcohol solution propylene and tertiary butyl hydroperoxide to anepoxidation reaction zone together with a catalytic amount of a catalystmixture of (aa) said initial ethylene glycol solution of said complex ofethylene glycol with said ammonium dimolybdate with (bb) a finalethylene glycol solution of a complex of ethylene glycol withammonium-containing molybdenum compounds derived from a precipitate ofsolid ammonium containing molybdenum compounds, in amounts sufficient toprovide an initial molar ratio of propylene to tertiary butylhydroperoxide of about 1.05:1 to about 2:1 and a concentration of about100 to 600 ppm of said catalyst mixture in said tertiary butyl alcoholsolution, e. establishing epoxidation reaction conditions in saidepoxidation reaction zone including a temperature of about 50° to about180° C. and a residence time of about 1 to about 5 hours to therebyreact said propylene with said tertiary butyl hydroperoxide and form anepoxidation reaction product comprising unreacted propylene, unreactedtertiary butyl hydroperoxide, propylene oxide, tertiary butyl alcohol,dissolved molybdenum-ethylene glycol catalyst complex, andoxygen-containing impurities, f. resolving the said epoxidation reactionproduct in a distillation zone into distillation fractions including adistillate propylene fraction, a distillate propylene oxide fraction, adistillate tertiary butyl alcohol fraction and a heavy liquiddistillation fraction composed primarily of tertiary butylhydroperoxide, tertiary butyl alcohol, oxygen-containing impurities anddissolved molybdenum-ethylene glycol catalyst complex, g. charging saidheavy distillation fraction to a precipitation zone and saturating saidheavy distillation fraction in said precipitation zone with ammonia tothereby form a liquid amination product containing a precipitate ofsolid ammonium-containing molybdenum compounds, h. charging saidamination product to a separation zone and therein separating the solidammonium-containing molybdenum precipitate therefrom, i. recovering saidsolid ammonium-containing molybdenum precipitate, j. charging saidrecovered solid ammonium-containing molybdenum precipitate to a catalystregeneration zone and mixing it therein with an amount of substantiallyanhydrous ethylene glycol sufficient to provide about 7 to about 20moles of ethylene glycol per gram atom of molybdenum contained in saidsolid ammonium-containing molybdenum precipitate to form an ethyleneglycol feed mixture, k. heating said ethylene glycol feed mixture insaid catalyst regeneration zone at a pressure of about 0 to 3,000 psigand a reaction temperature of about 70° to about 250° C. for a time,within the range of about 0.2 to 2 hours sufficient to form asubstantially solids-free ethylene glycol solution of a complex ofethylene glycol with the ammonium-containing compounds in said solidammonium-containing molybdenum precipitate, l. holding said solids-freesolution of said complex of ethylene glycol with the saidammonium-containing compounds in said catalyst regeneration zone at atemperature of about 90° to about 110° C. for a time, within the rangeof about 0.5 to 5 hours, sufficient to permit vaporization and removalof volatile by-products, including water, by an amount sufficient toprovide a final ethylene glycol solution containing about 16 to about 52wt. % of said complex of ethylene glycol with said ammonium-containingmolybdenum compounds and having a molybdenum content of about 6 to about20 wt. % and a water concentration of about 0.5 to 6 wt. %, and m.charging said thus-prepared final ethylene glycol solution of a complexof ethylene glycol with ammonium-containing molybdenum compounds to saidepoxidation reaction zone as said final ethylene glycol solution of acomplex of ethylene glycol with ammonium-containing molybdenum compoundsderived from a precipitate of solid ammonium containing molybdenumcompounds.
 5. A method as in claim 4 wherein the heavy liquiddistillation fraction is saturated with ammonia in the saidprecipitation zone under precipitation conditions including atemperature of about 20° to about 250° C. and a pressure of about 0 toabout 3,000 psig.
 6. A method as in claim 5 wherein the heavy liquiddistillation fraction contains from about 0.4 to about 0.8 wt. % ofmolybdenum, the said filtrate contains about 50 to about 200 ppm ofmolybdenum and the said precipitated ammonium-containing molybdenumcompounds contain about 40 to about 50 wt. % of molybdenum.
 7. Acontinuous method for the molybdenum-catalyzed preparation of tertiarybutyl alcohol and propylene oxide from propylene and tertiary butylhydroperoxide which comprises the steps of:a. continuously chargingsubstantially anhydrous ethylene glycol and substantially anhydrousammonium dimolybdate to a catalyst preparation reactor and mixing themtherein in amounts sufficient to provide about 7 to about 20 moles ofethylene glycol per gram atom of molybdenum contained in said ammoniumdimolybdate, b. continuously heating said mixture of ethylene glycol andammonium dimolybdate in said catalyst preparation reactor at a pressureof about 0 to 3,000 psig and a reaction temperature of about 70° toabout 250° C. for an amount of time, within the range of about 1 to 2hours sufficient to form a solids-free solution of a complex of ethyleneglycol with the said ammonium dimolybdate, c. continuously holding saidsolids-free solution of said complex of ethylene glycol with ammoniumdimolybdate in said catalyst preparation reactor at a temperature ofabout 90° to about 110° C. for an amount of time, within the range ofabout 0.5 to 5 hours, sufficient to permit vaporization and removal ofvolatile by-products, including water, by an amount sufficient toprovide an initial ethylene glycol solution containing about 16 to about52 wt. % of said complex of ethylene glycol with said ammoniumdimolybdate and having a molybdenum content of about 6 to about 20 wt. %and a water concentration of about 0.5 to 6 wt. %, d. continuouslycharging a tertiary butyl alcohol solution of propylene and tertiarybutyl hydroperoxide to an epoxidation reaction zone together with acatalytic amount of a catalyst mixture of (aa) said initial ethyleneglycol solution of said complex of ethylene glycol with said ammoniumdimolybdate with (bb) a final ethylene glycol solution of a complex ofethylene glycol with ammonium-containing molybdenum compounds derivedfrom a precipitate of solid ammonium containing molybdenum compounds, inamounts sufficient to provide an initial molar ratio of propylene totertiary butyl hydroperoxide of about 1.05:1 to about 2:1 and aconcentration of about 100 to 600 ppm of said catalyst mixture in saidtertiary butyl alcohol solution, e. establishing epoxidation reactionconditions in said epoxidation reaction zone including a temperature ofabout 50° to about 180° C. and a reaction time of about 1 to about 5hours to thereby react said propylene with said tertiary butylhydroperoxide and form an epoxidation reaction product comprisingunreacted propylene, unreacted tertiary butyl hydroperoxide, propyleneoxide, tertiary butyl alcohol, dissolved molybdenum-ethylene glycolcatalyst complex, and oxygen-containing impurities, f. continuouslyresolving the said epoxidation reaction product in a distillation zoneinto distillation fractions including a distillate propylene fraction, adistillate propylene oxide fraction, a distillate tertiary butyl alcoholfraction and a heavy liquid distillation fraction composed primarily oftertiary butyl hydroperoxide, tertiary butyl alcohol, oxygen-containingimpurities and dissolved molybdenum-ethylene glycol catalyst complex, g.continuously charging said heavy distillation fraction to aprecipitation zone and saturating said heavy distillation fraction insaid precipitation zone with ammonia to thereby form a liquid aminationproduct containing a precipitate of solid ammonium-containing molybdenumcompounds, h. continuously charging said amination product to aseparation zone and therein separating the solid ammonium-containingmolybdenum precipitate therefrom, i. continuously recovering said solidammonium-containing molybdenum precipitate, j. continuously chargingsaid recovered solid ammonium-containing molybdenum precipitate to acatalyst regeneration zone and mixing it therein with an amount ofsubstantially anhydrous ethylene glycol sufficient to provide about 7 toabout 20 moles of ethylene glycol per gram atom of molybdenum containedin said solid ammonium-containing molybdenum precipitate to form anethylene glycol feed mixture, k. continuously heating said ethyleneglycol feed mixture in said catalyst regeneration zone at a pressure ofabout 0 to 3,000 psig. and a reaction temperature of about 70° to about250° C. for an amount of time, within the range of about 1 to 2 hourssufficient to form a solids-free solution of a complex of ethyleneglycol with the ammonium-containing compounds in said solidammonium-containing molybdenum precipitate, l. holding said solids-freesolution of said complex of ethylene glycol with the saidammonium-containing compounds in said catalyst regeneration zone at atemperature of about 90° to about 110° C. for an amount of time, withinthe range of about 0.5 to 5 hours, sufficient to permit vaporization andremoval of volatile by-products, including water, by an amountsufficient to provide a final ethylene glycol solution containing about16 to about 52 wt. % of said complex ethylene glycol with saidammonium-containing molybdenum compounds and having a molybdenum contentof about 6 to about 20 wt. % and a water concentration of about 0.5 to 6wt. %, and m. continuously charging said thus-prepared final ethyleneglycol solution of a complex of ethylene glycol with ammonium-containingmolybdenum compounds to said epoxidation reaction zone as said finalethylene glycol solution of a complex of ethylene glycol withammonium-containing molybdenum compounds derived from a precipitate ofsolid ammonium containing molybdenum compounds.
 8. A method as in claim7 wherein the heavy liquid distillation fraction is saturated withammonia in the said precipitation zone under precipitation conditionsincluding a temperature of about 20° to about 250° C. and a pressure ofabout 0 to about 3,000 psig.
 9. A method as in claim 8 wherein the heavyliquid distillation fraction contains from about 0.4 to about 0.8 wt. %of molybdenum, the said filtrate contains about 50 to about 200 ppm ofmolybdenum and the said precipitated ammonium-containing molybdenumcompounds contain about 40 to about 50 wt. % of molybdenum.